One form of automotive suspension includes a coil spring seated in a lower seat in a wheel assembly and seated in an upper seat in the vehicle body or frame. The spring supports the weight of the vehicle and allows for reciprocating relative movement between the wheel and vehicle during road travel to isolate wheel disturbances from the vehicle body. Typically, a form of stop is provided between the vehicle wheel or axle and the vehicle body to limit travel of the wheel in the direction of the body and to prevent a metal surface the wheel or axle from "bottoming out" against the vehicle body metal. These stops are typically made of rubber or plastic urethane foam and are referred to as jounce bumpers.
Referring to FIG. 1, an example prior art suspension jounce bumper is shown. The jounce bumper 20 comprises two molded components, the bumper 22 and the additional isolator 24. The bumper 22 is molded from a plastic urethane foam and the isolator 24 is molded from a natural rubber, or alternatively, from urethane. In the vehicle suspension system, the radially extending portion 26 of jounce bumper assembly 20 is seated between a spring seat on a wheel assembly and a coil spring to serve as a bumper and travel limit between the vehicle wheel assembly and the vehicle body. The rubber spring isolator 24 in combination with the radially extending portion 26 of the jounce bumper 22 aid to isolate the high frequency component of wheel motion from the spring and vehicle body.
During a large magnitude suspension event, such as the vehicle wheel running over an object in the road or traveling through a series of potholes, the jounce bumper assembly 20 may contact a stop in the vehicle body and elastically deform responsive to the force of the contact of the jounce bumper assembly 20 against the vehicle body. As elastic deformation increases, the force provided by the bumper also increases, increasing to a limit at which the bumper stops the relative movement of the wheel assembly toward the vehicle body.